Modern designs for swimming pools and spas commonly provide for illumination of the pool or spa from beneath the waterline. For example, underwater light assemblies equipped with glass or plastic external lenses can be installed on and/or in the wall of a pool or spa below the waterline such that part or all of the external lens faces into the pool or spa, and is exposed to the water contained therein. Typically the external lens of such a light at least partially defines a water-tight illumination compartment of the light within which the light-emitting element or light emitter is mounted. While such an arrangement can be advantageous from the standpoint of illumination efficiency, it has long been recognized that such light assemblies can pose a risk of electric shock to bathers, especially if deliberate steps to mitigate this risk are not taken (e.g., during the product design phase). For example, should the water-tight integrity of the compartment containing the light emitter become compromised (e.g., while the pool and the light assembly are in use, and/or during pool or light assembly maintenance, etc.) and pool or spa water is admitted therein, a direct path of conductive water could be created along which current, previously contained within the light assembly, could stray into the main body of the pool or spa.
At least one commonly followed standard for safety with respect to such underwater lights, namely, Standard for Safety for Underwater Luminaires and Submersible Junction Boxes, UL 676, eighth edition, dated Jun. 9, 2003 and developed and maintained by Underwriter's Laboratories Incorporated of Northbrook Ill., recognizes that there are many different ways in which the risk to bathers of electrical shock from such underwater lights can be reduced and/or eliminated. In accordance with the UL 676 standard, many manufacturers have, for example, developed underwater lights with external lenses made of certain modern plastic and/or other polymeric materials, such as polycarbonate (e.g., from the LEXAN series of polycarbonate/plastics resins manufactured by General Electric Co.), or polycarbonate alloy, and in this way have obtained the desired safety certification. By choosing this design path, such manufacturers are essentially relying on the basic toughness and resiliency of such materials to avoid lens degradation via such stressors as impact shock, thermal shock, fatigue-inducing thermal cycling, etc. Unfortunately, such materials also have drawbacks in comparison to more traditional lens materials, such as optical glass and/or similar (i.e., glass-like) materials. For example, such plastic or polymeric materials tend to become internally cloudy over time, and are typically not very scratch-resistant. This limits their utility, at least with respect to certain underwater light markets, such as the market for commercial and high-end consumer pool and spas, in which premiums are often placed on such characteristics as overall aesthetic appearance, and/or sustained brightness/luminosity, etc.
Seeking to service such markets, some other manufacturers produce high-quality underwater lights equipped with external lenses made from the more traditional glass or glass-like materials. Unfortunately, such lenses tend not to exhibit the type of strength and toughness which characterizes the above-mentioned plastic and polymer-type lenses. Accordingly the external lenses of such underwater lights are characteristically more likely to fail the impact and/or thermal shock tests associated, for example, with the above-mentioned UL 676 safety standard. In such circumstances, in order to achieve the desired safety certification with respect to the risk of shock from stray electrical current, design solutions must generally be devised and implemented which ensure that, even in the event of a complete fracture of the external lens, resulting in a complete flooding of the light fixture and/or a short in the applicable electrical and/or electronic circuit, the shock risk to nearby bathers is nevertheless still acceptable. Some such design solutions are disclosed in U.S. Patent Application Publication No. 2002/0101198, and in U.S. Pat. Nos. 3,949,213; 4,234,819; 5,545,952; and 5,842,771. Accordingly, design solutions for underwater lights shown to reduce the shock risk to nearby bathers to acceptable levels are both necessary and desirable.
In addition to contending with issues relating to the risk of electrical shock to nearby bathers, manufacturers of high quality underwater lights must ensure that, to the extent excessive heat is generated by the various components thereof, e.g., light-emitting elements, transformers, microprocessors (if applicable), etc., such heat is promptly and efficiently conducted away from the light. In particular, certain types of underwater lights, e.g., underwater lights equipped with one or more LED arrays, tend to produce heat in such quantity that the effectiveness of the methods and apparatus employed therein for heat removal is critical to issues such as safe operation and product reliability/durability. Especially in light of the current trend toward brighter and brighter underwater lights, including underwater lights producing white light via the simultaneous illumination of separate arrays of blue, red and green LEDs, the development and deployment of effective new methods and apparatus for conducting heat from underwater lights is an industry priority.